[PATCH] mmc: core: Fix max_dtr passed to SD drive strength selection

[PATCH] mmc: core: Fix max_dtr passed to SD drive strength selection

[Shawn Lin]

sd_select_driver_type() passes card->sw_caps.uhs_max_dtr to
mmc_select_drive_strength(), but that field is only assigned later by
sd_set_bus_speed_mode().  A card initialized for the first time thus
gets max_dtr=0, while a re-initialized card (system resume or
hw reset recovery reuse the card struct) gets the stale value from the
previous initialization.

No in-tree driver implementing ->select_drive_strength() (AMD and Intel
SDHCI) actually looks at max_dtr, so there is no functional impact
today.  Still, compute the frequency from the bus speed mode that
sd_update_bus_speed_mode() has already selected, so the core doesn't
hand out a bogus value, and use the same helper in sd_set_bus_speed_mode()
to keep a single mapping.

Signed-off-by: Shawn Lin <shawn.lin@linux.dev>
---

 drivers/mmc/core/sd.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index c763efb..5ba4e2d 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -417,6 +417,22 @@ int mmc_sd_switch_hs(struct mmc_card *card)
 	return err;
 }
 
+static unsigned int sd_get_bus_speed_dtr(struct mmc_card *card)
+{
+	switch (card->sd_bus_speed) {
+	case UHS_SDR104_BUS_SPEED:
+		return UHS_SDR104_MAX_DTR;
+	case UHS_DDR50_BUS_SPEED:
+		return UHS_DDR50_MAX_DTR;
+	case UHS_SDR50_BUS_SPEED:
+		return UHS_SDR50_MAX_DTR;
+	case UHS_SDR25_BUS_SPEED:
+		return UHS_SDR25_MAX_DTR;
+	default:
+		return UHS_SDR12_MAX_DTR;
+	}
+}
+
 static int sd_select_driver_type(struct mmc_card *card, u8 *status)
 {
 	int card_drv_type, drive_strength, drv_type;
@@ -427,7 +443,7 @@ static int sd_select_driver_type(struct mmc_card *card, u8 *status)
 	card_drv_type = card->sw_caps.sd3_drv_type | SD_DRIVER_TYPE_B;
 
 	drive_strength = mmc_select_drive_strength(card,
-						   card->sw_caps.uhs_max_dtr,
+						   sd_get_bus_speed_dtr(card),
 						   card_drv_type, &drv_type);
 
 	if (drive_strength) {
@@ -490,28 +506,25 @@ static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
 	switch (card->sd_bus_speed) {
 	case UHS_SDR104_BUS_SPEED:
 		timing = MMC_TIMING_UHS_SDR104;
-		card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR;
 		break;
 	case UHS_DDR50_BUS_SPEED:
 		timing = MMC_TIMING_UHS_DDR50;
-		card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
 		break;
 	case UHS_SDR50_BUS_SPEED:
 		timing = MMC_TIMING_UHS_SDR50;
-		card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
 		break;
 	case UHS_SDR25_BUS_SPEED:
 		timing = MMC_TIMING_UHS_SDR25;
-		card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
 		break;
 	case UHS_SDR12_BUS_SPEED:
 		timing = MMC_TIMING_UHS_SDR12;
-		card->sw_caps.uhs_max_dtr = UHS_SDR12_MAX_DTR;
 		break;
 	default:
 		return 0;
 	}
 
+	card->sw_caps.uhs_max_dtr = sd_get_bus_speed_dtr(card);
+
 	err = mmc_sd_switch(card, SD_SWITCH_SET, 0, card->sd_bus_speed, status);
 	if (err)
 		return err;
-- 
2.7.4